Created attachment 143026 [details]
the dmesg got after issue happened.
VGA of Host Machine:
00:02.0 VGA compatible controller : Intel Corporation Device [8086:3e9b] (prog-if 00 [VGA controller])
Monitor: Dell P2317H (can also reproduce it on other monitor)
steps to reproduce:
1. connect external monitor
2. see screen on external monitor
3. get flicker on external monitor
4. switch display mode by "windows+p" still get flicker or even dark screen.
5. see error message on dmesg
[drm:intel_dp_get_link_train_fallback_values [i915]] *ERROR* Link Training Unsuccessful
this issue could be also reproduced by main line kernel 5.0.0-rc1
Please try to reproduce the error using drm-tip (https://cgit.freedesktop.org/drm-tip) and kernel parameters drm.debug=0x1e log_buf_len=4M, and if the problem persists attach the full dmesg from boot.
Created attachment 143148 [details]
dmesg from drm-tip 2019-01-18
No more "[drm:intel_dp_get_link_train_fallback_values [i915]] *ERROR* Link Training Unsuccessful" but I still observe the issue.
Alex, Do you still see the issue? Can you please attach the latest dmesg from latest kernel (preferably with drmtip)?
My apologies for not responding on this issue.
Alex, any updates here?
Sorry for response late. This issue not happened to another machine which is same configuration as the problematic one. So, we treated it as hardware issue.
Thanks for your following.